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I was making a voltage tester with the Uno and the input was A0. When I went above 10 volts into A0, that pin stopped working. Is it possible to fix the pin? If so, what do I do?

Logan S. Colon
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    No. It's dead. Time to move on to the next pin and see how long that one lasts... – brhans Oct 01 '20 at 03:05
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    Bag it and tag it and get another Uno. Write "NG" on the tag. "NG" is understood all the world around to mean "No Good." – user57037 Oct 01 '20 at 03:11
  • Does this answer your question? https://electronics.stackexchange.com/a/518127/35022 – MarkU Oct 01 '20 at 03:16
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    @mkeith except at Arduino, where the "Arduino NG" was actually a product. But I digress... You are correct, that input is clearly gone, the rest of the chip should be looked on with extreme suspicion and used only as a last resort in unimportant temporary experiments. Replacing the MCU on the board would be a good experience. – Chris Stratton Oct 01 '20 at 03:22
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    I would cut the pin off the module. It would be pretty clear to your future self that you knew it didn't work and made it obvious regardless of nomenclature. If you're brave enough to continue using it that is. – DKNguyen Oct 01 '20 at 03:23
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    Is there an Arduino “NFG”? Because that’s what we usually mark such devices. Or “FUBAR” if there is room. – Spehro Pefhany Oct 01 '20 at 06:24
  • This is a good example of why It is a must to read the documentation before jumping directly to the application. – emre iris Oct 01 '20 at 07:28
  • NFG and FUBAR are good for domestic consumption. I stick with NG when overseas. – user57037 Oct 02 '20 at 03:56

2 Answers2

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You've definitely killed A0.

You may have killed other pins too so I'd avoid using that device again because you may end up chasing phantom problems which are going to slow you down.

mhaselup
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Your A0 pin is killed. Every I/O pin on a microcontroller is protected with a diode clamp, if the voltage on the IO pin goes above or below the supply voltage or very small time then it is clamped. But if it stays there for a longer time the clamp diode burns internally.

So, for using IO as input always use around 1KΩ series resistor and an external Zener clamp to avoid damaging of Microcontrollers Pin. as shown here!

Deepak
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